PERMEABLE INTERLOCKING PAVERS F A C T S H E E T
Permeable pavement systems have structural units that include void, or open, spaces, allowing
stormwater to infiltrate and get treated and stored in an underlying gravel base. The stormwater is
then filtered through native soils or is discharged through an underdrain. Permeable pavement systems
include, permeable pavers (bricks or blocks), along with pervious concrete and porous asphalt. Permeable
pavers use pervious void space located between the pavers that is
often filled with small aggregate.
Permeable pavement systems are designed to reduce peak flows and
volumes of stormwater runoff. They are advantageous for groundwater
recharge, particularly in areas where land values are high, as vehicles
can drive and park on this stormwater practice. Placement of these
systems where in-situ subsoils have an infiltration rate greater
than 0.5 in./hr. is recommended. When underlying soils have low
permeability, permeable pavement systems can utilize an underdrain
to return filtered runoff to the conveyance system. There are many
different shapes, styles, and materials used to create the pavers used in
these systems. Permeable Pavement is designed to reduce runoff and
treat the water quality rain event (1.2 inches); however they can also
be designed to handle larger storm events and store larger volumes of
runoff. The ratio of impervious area to permeable paver surface area
should be no greater than 3:1.
PERMEABLE PAVEMENT POLLUTANT REMOVAL1
80% of suspended solids
50% of phosphorus
50% of nitrogen
60% of metals
SMALL AGGREGATE
PAVERS
1 2 3
As with any type of green infrastructure, permeable pavers require maintenance to ensure continued
functionality. It is important to avoid compaction and clogging of these pavement systems, beginning with
construction. Undesirable vegetation, sediment accumulation and debris are common culprits of clogged
permeable pavement systems. General inspection and assessment of three critical features can keep the practice
operational. Street sweeping and hydro-excavation can be effective for source control and routine maintenance
of the top layer. Surface cleaning is required to remove debris and undesired vegetation that clog the top layer of
the permeable pavement system. Locations that are highly trafficked or near overhanging vegetation may need
more frequent surface cleaning to maintain higher infiltration rates.
Three Critical Features to Inspect
Drainage Area Inlet and Outlet Structures Pavement Surface The condition of the drainage area If inlet or outlet structures are The void space between the surface of
and surrounding landscape that will impeded, this could mean a number the permeable pavers is the primary
contribute runoff to the practice of things. Structural damage might location for infiltration of stormwater.
is essential to its overall function. be present, there might be evidence Physical clues such as accumulation
Unstable areas that are sources of of erosion, or runoff may not be of fine sediment, stains, standing
sediment or drainage ways that have flowing over the pavement surface water, and paver settling are evidence
pollutants such as trash, debris, and maintenance is required to restore of surface clogging and subsequent
sediment, and grass clippings can function. maintenance needs. Any missing
hinder the performance of the aggregate needs to be replaced to
permeable pavement by clogging the maintain optimal performance of
pavement surface or contributing the system. Pavers that have been
additional nutrient and pollutant loads. damaged (signs of cracks, splitting, or
structural damage) need to be replaced
to maintain public safety.
Maintenance costs vary based on many factors. The maintenance
cost as a percentage of capital cost is estimated at 3-5%; however,
more robust local datasets are needed.2
1 Georgia Stormwater Management Manual. Atlanta, 2016. 2016 Edition. https:// atlantaregional.org/natural-resources/water/georgia-stormwater-management-manual/
2 Clary, J. and Piza, H. (2017). “Cost of Maintaining Green Infrastructure.” ASCE. Reston, VA.
For more a more detailed inspection checklist reference:
gacoast.uga.edu/stormwater-management